1. Technical Field
The present invention relates to an image processing technique used when one dot image is displayed using four sub-pixels.
2. Related Art
In color display devices or output devices, for example, three colors of RGB sub-pixels correspond to one dot of an image to be displayed, and gray-scale levels (brightness) of the individual sub-pixels are controlled to display the color of the one dot. However, in this construction, since the range of displayable colors is limited, a technique for displaying one dot using four color sub-pixels has recently been proposed (for example, see JP-A-9-238262).
However, in image outputting devices such as a printer, drawing points can be freely controlled, but in image display devices such as a liquid crystal device, the positions of sub-pixels are fixed. Further, since in the liquid crystal device, or the like, generally, display is performed using RGB sub-pixels, in the case of displaying a color image in four sub-pixels, it is needed to change one square dot formed by three sub-pixels into one square dot formed by four sub-pixels.
Therefore, since an image display device which displays one dot by using four sub-pixels has disadvantages such as enlargement of displayable color range, a design change, or increased cost due to the design change such an image display device has not become widespread.